According to the WHO, it could take six to nine months to bring Ebola under control and a road map with its USD 490-million plan has been released to try to contain the outbreak in the stipulated time.

As of August 26, 1,552 people had been confirmed dead from Ebola in four countries, Sierra Leone, Liberia, Guinea and Nigeria while 3,062 had been infected.

Bruce Aylward, the WHO's head of emergency programmes, has warned that the actual caseload could be "two to four times higher than the number of cases you see reported".

Liberia was the worst affected with 694 deaths; 422 people have died in Sierra Leone; and 430 in Guinea, where the virus emerged at the start of the year. Nigeria has now recorded six deaths.

Scientists meanwhile said the first human trials of a potential vaccine will start next week using a product known as the NIAID/GSK Ebola vaccine candidate made by pharmaceuticals giant GlaxoSmithKline and the US government.